We built this legacy application back in 2007 and have a major upgrade in 2009 and has been running since then but then there is not much activity since 2014. Then reassure-ct again in late 2015.
Error on the session
This is a bit shocking cause the .cs file is never being changed since 2009 !!!
Solution: Change the code accordingly to handle the missing handling of Session.
Find another one that is related to Debug mode. Set: <compilation debug=”false”> in Web.Config. There is a possibility that there is a bug previously and didn’t set back into False.
Validation of ViewState MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validation key and validation algorithm. AutoGenerate cannot be used in a cluster.
Turn out that the database server is registered under web.config still using the new production server. Need to change to a new server.
The application message came up: “You have a duplicate in MostLeast Preferred section. The option only can be used once of those questions. Please re-select it again.” Check the answer in the application and no duplicate answer.
Turn out that the actual matrix answer records in the database table have a duplicate for that particular question. Looks like entering twice. Not sure causing this at this stage. However, removing the duplicated entries solves the problem.
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